(1) Field of the Invention
The present invention relates to a motorcycle upper-cowl which covers the handlebars, instruments and the like in the top portion of the front part of a motorcycle to reduce air resistance whilst making the front turn signals easily visible and also providing an efficiency-improved air intake for guiding air for engine supercharging, cooling heat exchanger, etc.
(2) Description of the Prior Art
A motorcycle upper-cowl is mounted to cover the handlebars, instruments, etc., in the portion of the front part of the motorcycle and is configured to smoothly lead air along its exterior surface from its front part to the rear outer sides during driving to reduce its air resistance. Typically, the upper cowl is integrally formed with an air intake that opens forward for guiding air for engine supercharging, heat exchanging and cooling, etc.
Arranged in the front part of a motorcycle are front turn signals. These turn signals are formed separately from, or integrally with, the upper-cowl. In either case, the turn signals are projected from their surroundings in order to secure their visibility.
A conventional upper-cowl for a motorcycle typically has an air-intake of which the opening is directed forward in order to secure improved intake efficiency. Therefore, this shape of the conventional upper-cowl made it difficult to minimize the air resistance thereof.
Illustratively, as shown in FIG. 1, the overall external surface of the upper-cowl is formed with a streamlined, basic cross-sectional shape (basic planar sectional shape) C such as an arc, parabola or some analogous section, which curves with its tangent being gradually directed toward the rear, from the forward part (the upper end in FIG. 1) to the rear outer sides (to the lower end in FIG. 1). This shape of the upper-cowl can produce an optimized, smooth airflow along its external surface, thus leading to a sharp reduction in air resistance. However, because most upper-cowls have headlamps 112 and 112 in the center thereof, a streamlined upper-cowl has openings of air intakes 113 and 113 in the outer, slanted portions on the sides of a headlamp cover 111. That is, the openings are not directed frontward, giving rise to the problem of the intake efficiency of air intakes 113 and 113 being lowered.
Further, in order to secure the visibility of the turn signals, it is necessary to arrange the turn signals so that they are projected from their surroundings in the upper-cowl whatever shape the upper-cowl has. Therefore, these projections degrade the air rectification of the upper-cowl, giving rise to the problem of increase in air resistance.